1. Field of the Invention
The present invention relates to manway covers in general and especially to a quick-opening, internal manway cover providing access to the various trays within refinery distillation towers.
2. Description of the Prior Art
A modicum of patented and unpatented literature has been published regarding various manway covers and means for securing them in the manway.
U.S. Pat. No. 2,105,501 teaches a bubble tray with a circular opening manway which is held in place by a formed lip, flange, and J-bolts with springs which may be opened without the use of tools. U.S. Pat. No. 2,332,243 teaches a method for fastening manway covers to distillation column trays by means of threaded bolts which may be removed from above or below the tray. U.S. Pat. No. 2,611,596 teaches securing a manway cover detachably to flanges of the tray by means of a plurality of clamps using a wrench.
Glitsch, Inc. of Dallas, Texas, manufactures a manway cover under the trademark name, "Minute-Manway" which is a one-piece, rectangular cover hinging in the middle with dogs located near the center of the cover and where the sides of the cover opposite the hinged center fit under lips which extend above and are affixed to the surface of the tray. The cover is positioned so that the ends will slide under the lips affixed to the tray when the hinged center moves into a closed position.
The present invention embodies a manway cover consisting of two similar panels which interlock with each other and with the manway edge to remain in place.